This invention is directed to the delivery of a liquid containing therapeutic or diagnostic material to a desired site within a patient's body. The invention has particular application to procedures in coronary or peripheral arteries such as percutaneous transluminal coronary angioplasty (PTCA).
PTCA is a widely used procedure for the treatment of coronary heart disease. In this procedure, a balloon dilatation catheter is advanced into the patient's coronary artery and the balloon on the catheter is inflated within the stenotic region of the patient's artery to open up the arterial passageway and thereby increase the blood flow through the artery.
One type of catheter frequently used in PTCA procedures is an over-the-wire type balloon dilatation catheter. Commercially available over-the-wire type dilatation catheters include the SIMPSON ULTRA LOW PROFILE.RTM., the HARTZLER ACX.RTM., the HARTZLER ACX II.RTM., the PINKERTON 0.018.TM. and the ACS TEN.TM. balloon dilatation catheters sold by the assignee of the present application, Advanced Cardiovascular Systems, Inc. (ACS).
Coronary and peripheral angioplasty procedures have met with considerable success and have greatly reduced the need for by-pass surgery. However, in some instances the physical dilatation of the stenosis during the angioplasty procedure has been found to be inadequate by itself to effectively treat the stenotic region. Restenosis, the reforming of plaque in an artery, is a problem in over 30% of the coronary angioplasty procedures, and in many cases the restenosis is severe enough to require redilatation. Restenosis is believed to occur due to the proliferation of smooth muscle cells in the region of the dilatated artery.
It has been proposed to use heparin and other types of therapeutic agents in the stenotic regions of a patient's coronary arteries in order to reduce the incidence of restenosis. It has also been suggested to utilize therapeutic agents such as urokinase, streptokinase and tissue plasminogen activator (TPA) to treat thrombus in stenotic regions. Other drugs and therapeutic agents have also been suggested. However, the systemic use of therapeutic and diagnostic agents is not very desirable because the patient's entire body must be medicated to a very high level in order to treat or diagnose a small region in the patient's vasculature and frequently these therapeutic and diagnostic materials can be toxic at the levels needed for effective treatment or diagnosis.
Site specific delivery systems for drugs, therapeutic agents and diagnostic agents through catheters are known but such systems have not always been effective. Usually, only the surface tissue is treated. Wolinsky et al. in Journal of the American College of Cardiology, Vol 17, No. 6, 1991, 174-178; Journal of the American College of Cardiology, Vol. 15, No. 2, 1990, 475-481; Journal of Interventional Cardiology, Vol. 2, No. 4, 1989,219-228; and Goldman et al. in ATHEROSCLEROSIS, 65 (1987) 215-225, describe a therapeutic or diagnostic fluid delivery system which includes a perforated balloon to infuse therapeutic or diagnostic fluids into artery walls. See also U.S. Pat. No. 5,087,244 (Wolenski). Apparently, in the procedures described in the above references, liquid is maintained between the surface of the balloon and the adjacent tissue and the inflation of the balloon creates a relatively high fluid pressure and forces the fluid to permeate into the arterial tissue. However, during these procedures it has been found that a substantial amount of fluid is frequently driven away from the delivery site and thereby lost, apparently due to fluid leaking between the balloon and the stenosis. Ring type balloons have been disposed adjacent both ends of the perforated balloons in an attempt to minimize the loss of fluid, such as shown in U.S. Pat. No. 4,636,195 and U.S. Pat. No. 4,824,436, but the additional inflation lumens needed to inflate the ring balloons complicate the catheter structure and thus the manufacturability of the product. These designs also significantly increase the profile of the shaft and greatly limit the usefulness of the catheter. Moreover, because the inflated balloons of these designs block arterial passageways, the period for fluid delivery must necessarily be quite short, particularly in a patient's coronary arteries.
What has been needed and heretofore unavailable is a means to deliver therapeutic agents, diagnostic agents and the like deep within tissue without both damage to the tissue and significant systemic loss of the fluid material being delivered. Of particular need is a means to deliver such a fluid so as to provide long term availability of the delivered therapeutic or diagnostic material without significant loss thereof. The present invention satisfies these and other needs.